Carburetor metering control



June 28, 1955 J. T. vv. Mesi-:LEY ET Ax. Zamw CARBURETOR METERING CONTROL Filed Oct. 20, 1952 2 Sheets-Sheet l INVENTORS JAMES ''.VV. MOSELEY ATTQBNEY HROLD A. CARLSON June 2, i955 J. T. W. NIOSELEY ET AL CARBURETOR METERING CONTROL Filed OOL. 20, 1952 2 Sheets-Sheet 2 JAMES TW.i\/iOSEl EY BY HAROLD ACARLSON ATTORNEY CARBURETOR METERING CONTROL .lames T. W. Moseley, Richmond Heights, and Harold A.

Carlson, Brentwood, Mo., assignors to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application October 20, 1952, Serial No. 315,676

1 Claim. (Cl. 26.1--51) This invention relates to carburetors for internal combustion engines and consists particularly in novel fuel metering means involving both manual and suction responsive features.

Read Patent No. 2,208,702 discloses and claims fuel metering means for an automotive carburetor which conv sists in a one-way, operative connection between the carburetor throttle and the metering pin, arranged so that upon opening of the throttle valve, the metering pin is positively shifted in its fuel enriching direction. The metering pin is also operated by a suction motor which is responsive to increasing suction in the carburetor induction conduit posterior to the throttle and which acts in opposition to a spring to shift the metering pin in its mixture leaning direction as far as permitted by the above-mentioned throttle connection.

It has been found that when such a carburetor is operated under some conditions, particularly at high altitude, the added enrichment resulting from the suction responsive action of the metering pin is undesirable, causing loss of power and waste of fuel, because the carburetor tends to ow too rich at high altitudes where the air is less dense and less depression exists in the intake manifold during operation. We have found that the difficulty can be cured in the type of carburetor mentioned by providing a yieldable stop element which may be shifted into a position to prevent the suction action of the metering pin while permitting shifting of the pin by the positive one-way connection to the throttle valve. In other words, we propose to eliminate varying the metering of fuel in accordance with changes in suction conditions so that the metering control becomes solely manual or throttle operated.

In the accompanying drawings which illustrate the invention:

Fig. 1 is a side view and partial vertical transverse section showing a carburetor embodying the invention.

Fig. 2 is a view taken at 90 to Fig. l and showing the carburetor mostly in section to illustrate the underlying parts.

Fig. 3 shows a part of the structure in Fig. 2 with the throttle valve shown in a fully open position.

Fig. 4 is a detail view of the same structure, but showing the yieldable stop element withdrawn to release the metering pin for suction action.

The carburetor shown in Fig. 1 is of the dual downdraft type including a central air inlet horn 6 mounting a choke valve (not shown) operated by well-known automatic control mechanism within a housing 7. Butterily throttle valves. as at 8, are mounted on a shaft 9 extending across the outlet portions of the mixture conduits 10. These outlet portions are flanged as at 11 for attachment to the engine intake manifold (not shown).

The constant level fuel bowl, generally indicated at 14, extends around the mixture conduits and encloses a pair of oats, one of which is shown at 15, connected together by a yoke 16 and by means of a central arm 17 to a pivot support pin 1S mounted in the bowl walls. A fuel inlet 2,711,885 Patented June 28, 1955 fr 1C needle valve 19 located in the inlet valve seat member 20 normally rests upon and is actuated by yoke extension i7 so as to admit suiicient fuel through tapped inlet 21 to maintain fuel in the bowl at a substantially constant level, as is well known. Inlet 21, of course, is connected by suitable tubing to a fuel pump (not shown).

At one side of the bowl are located main metering orificc elements 24 for metering the fuel supplied to upwardly inclined main fuel passages 25, leading to main nozzles 26 opening into primary venturi tubes 27, and idling systems 28, 29, and 30. A main nozzle and an idling system are provided for each mixture conduit, only one of each being shown, for simplicity. Metering orifice elements 24 are variably controlled by metering pins 32, carried at their upper ends by a cross bar 33 centrally connected by means of a link 34, guided as at 35, to a piston 36 working in a cylinder 37 which is connected by means of a passage 38 to at least one of the carburetor induction conduits posterior to the throttle valve therein. Piston 36 is constantly urged upwardly by a coil compression spring 39.

Piston link 34 has a longitudinal slot 40 which receives a projecting finger 41 on an arm 42 which is rigidly secured to a countershaft 43 rotatably mounted above bowl cover 44. A second arm 45 also rigid with the countershaft operates the usual accelerating pump (not shown). At the left end of countershaft 43 (Fig. 1) there is rigidly secured a lever 46 which is connected by means of a link 47 to an arm 48 rigid with a projecting end of throttle shaft 9. The arrangement is such that upon opening movement of the throttle disks, countershaft 43 and arm 42 are rotated clockwise with respect to Fig. 2 whereby finger 41 tends to elevate metering pins 32 toward their rich positions. Slot 40 in piston link 34 provides considerable lost motion for independent lifting of the metering pins, under the influence of compression spring 39, when the suction in the carburetor induction conduits drops below a predetermined degree. As the throttle valves are closed, suction applied to the piston 36 increases so that the piston is depressed and acts through cross bar 33 to lower the metering pins in the leaning direction. Thus, lost motion slot 40, normally limits the extent of action of the metering pins upon variation of suction and independently of throttle movement.

However, in order to eliminate this last-mentioned function, particularly for high altitude operation, we provide a stop plunger 50, slidably received in the lower reduced portion of a threaded sleeve 51 and limited in its downward motionrelative thereto by engagement of a head 52 on the plunger with the internal shoulder 51a in the sleeve. The stop plunger is constantly urged downwardly by a coiled compression spring 53 bearing at its lower end against' a foot 54 on the plunger. When the plunger is in its lowered stop position, as in Fig. l, this foot bears against cross bar 33 which carries the metering pins so as to resist upward movement thereof. Spring 53 is slightly stronger than suction piston spring 39 so that, in this position of the parts, the suction responsive action of the metering pins is eliminated. However,

` spring 53 may yield when the throttle valves are opened as in Fig. 3 to permit the consequent enriching movement of the metering pins. Sleeve 51 has a kerf 55 in its upper end for application of a screw driver to advance or retract the sleeve and, with it, yielding stop pin 50.

Fig. 4 shows sleeve 51 and stop pin 50 withdrawn upwardly so as to no longer interfere with free motion of cross bar 33 and the metering pins. In this case, the metering pins may be shifted upwardly by compression spring 39 upon dropping of the suction in the mixture conduits, to produce the normal, suction metering effect mentioned above. Of course, in intermediate positions of sleeve 51, the resilient stop pin has only a partial effect L) upon the action of the metering pins, that is, tends to reduce the enriching movement of the pins and, therefore, this feature may be used in some instances as a Calibrating factor.

The operation of the device has been fully described above in connection with the description of the structure so that repetition thereof should not be necessary for a clear understanding of the invention. Obviously, the particular type of carburetor, as shown, is not important and the metering arrangement may be Varied as can the positioning of the adjustable resilient stop. The invention makes it possible to adapt the carburetor for operation at high altitudes simply by lowering of sleeve 51, as shown in Figs. l, 2, and 3, so that the metering pins or other metering elements need not be changed as has been the practice heretofore.

The normal, low altitude position of the stop is shown in Fig. 4.

The exclusive use of all modilications as come within the scope of the appended claim is contemplated.

What is claimed is:

In a carburetor for an internal combustion engine, an induction conduit having a throttle and main fuel discharge nozzle therein, a fuel bowl adjacent said conduit having a cover and a metering orifice in its lower portion communicating with said nozzle, a metering pin with a varying metering portion projecting into said orifice, said pin extending upwardly through the top of said bowl, a one-way operative connection between said pin and said throttle for shifting said pin in its mixture enriching direction as said throttle is opened, a rst spring normally urging said pin in the same direction, a suction motor operative responsive to the existence of relatively high suction in said induction conduit for yieldingly urging said pin in opposition to said spring, a yielding stop mounted abo-.fe said fuel bowl adjacent with said pin, a second spring reacting between said stop and said bowl cover and normally urging said stop toward a position to interfere with movement of said pin by said first spring, and means to shift said stop from said position to a second position free of said pin and its operating mechanism.

References Cited in the tile of this patent UNITED STATES PATENTS 1,802,321 Mabee et al Apr. 21, 1931 1,869,821 Moore Aug. 2, 1932 2,477,481 Ericson July 26, 1949 2,611,592 Anderson Sept. 23, 1952 

